Home automation protocols

[Tom Metro]

I know there are a few users of home automation devices on this list. At 
the last meeting someone suggested a possible use for the hacked Western 
Digital NAS might be as a home automation server.

So of the emerging new home automation protocols, what's your 
preference, and why?

Although ideally I'd like to go with an open protocol, the choices in 
that area aren't really backed up with any products. I guess if 
manufacturers don't think they can lock-in their customers, they don't 
feel it is worth the effort to make the products.

ONE-NET[1] and Internet-0[2] (IP over power lines) are examples of the 
fully open protocols. I haven't ran cross any devices using these protocols.

Zigbee[3], an RF mesh network, is based on an IEEE standard, but 
requires licensing fees (I don't know if that is accomplished through 
patents, or if they just license the right to use the trademarked name; 
the referenced article says the spec is available for free to 
non-commercial developers). I hadn't noticed any Zigbee products at home 
automation sites, but a search specifically for it does turn up a small 
smattering of products (an expensive touch screen controller; a few 
light switches). A search also turns up some products aimed at 
electronics hobbyists (transceiver boards; boards that interface with 
the Arduino microcontroller; see sparkfun.com).

On the proprietary side of things...

Initially I was leaning towards INSTEON[4], as in addition to it using a 
dual mesh network (power line carrier and RF), it also claims to have 
some interoperability with X-10. (Despite the unreliable and poor 
quality of X-10, there are still some legacy devices where some 
interoperability is desired.)

The problem with INSTEON seems to be that the modules are a bit more 
expensive, there appears to be only one manufacturer, and the X-10 
interoperability is actually rather limited.

Perhaps the best choice is Z-Wave[5], an RF-only mesh network, that was 
developed by a chip manufacture (Zensys[6]), who provides the chips to 
100+ device manufacturers. The multi-vendor competition makes the module 
prices more competitive, and there's a decent variety of modules for a 
protocol that's only been out for a few years, but even more interesting 
is that I see you can buy a radio/CPU module from Digikey[7] for $13. 
That has good hacker possibilities for making custom sensors. (Looks 
like the programmer will run you $500, but maybe cheaper third-party 
alternatives will appear.)

There seems to be a big push by the Z-Wave Alliance to try and get 
consumer electronics manufacturers to switch from IR remotes to Z-Wave 
RF remotes. Though one of the first products in that area - a home 
theater universal remote - seems to get complaints on the message boards 
for failing to implement the Z-Wave software stack correctly.

Another area they seem to be going after is security sensors, though it 
isn't clear from what I've read that the encryption used by Z-Wave is 
all that strong. (Zigbee, in contrast, has an optional high security 
mode.) They address Z-Wave security in an FAQ[8], but the answer is 
unsatisfactory. They talk about it from the perspective of commercially 
available controllers, and how your neighbor with a store-bought 
controller won't be able to mess with your devices. Nothing they say 
dismisses the possibility of using a custom Z-Wave radio attached to a 
PC to "war drive" and sniff out house codes and sensors.

Currently there is no cheap solution for X-10 interoperability. 
Wayne-Dalton (yes, the garage door opener manufacturer) has an X-10 
bridge[9] "available soon," but it's supposedly been in that state for a 
long time. The workaround is to do the bridging through a home 
automation controller, which typically runs $300+, or put interfaces for 
both protocols on the PC you're using as a controller.

What I haven't looked at much yet is how friendly these proprietary 
protocols are for open source software developers. I see [also 8]:

   Is there open source code for Z-Wave?

   Absolutely. Some of our vendors have embraced the open source and
   hobbyist communities extensively. For example, many free projects have
   cropped up using the Intermatic/Microsoft HA102 starter kit (with the
   ControlThink Z-Wave PC SDK). The xPL project also provides open source
   support for Z-Wave products.

And initial poking around shows that both Z-Wave and INSTEON are 
supported by some of the open source home automation tools. I don't 
currently use any of these tools, so I don't know which are the better 
packages that, if they supported only one of the two, might drive the 
decision for which protocol to pick.

Also, Linux Journal recently had a review of the Vera Z-Wave Home 
Control System[10], a small Linux-based home automation controller 
appliance, so there's already some evidence of them playing nice with 
open source. At $300, unless you want a turn-key solution, it would be 
more economical to pair up a $50 USB Z-Wave interface (assuming drivers 
are available) with any of several sub-$100 Linux appliances (like a 
Linksys NSLU2).

  -Tom

1. http://en.wikipedia.org/wiki/ONE-NET
2. http://www.mywiseowl.com/articles/Internet-0
3. http://en.wikipedia.org/wiki/Zigbee
4. http://en.wikipedia.org/wiki/INSTEON
5. http://en.wikipedia.org/wiki/Zwave
6. http://www.zen-sys.com/modules/Zensys/
7. 
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=3539948&FV=fffc02bf
8. http://www.zwaveworld.com/ask/ask8.php
9. http://www.wayne-dalton.com/access/access_controllers.asp
10. http://www.smarthomeusa.com/ShopByManufacturer/mi-casa-verde/Item/VERA/

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/